Implants which are used for insertion into bone, for example for attachment of artificial teeth, are known per se. Different types of implant systems are known, for example two-part implant systems. Said two-part implant systems comprise first an anchoring part for anchoring within the bone and second an abutment. Onto the abutment prosthesis elements, such as bridges or crowns, are screwed or cemented.
Further implant systems comprising an anchoring part and an abutment are known, wherein the anchoring part of the implant system is submerged at bone level (so called submerged implants) so that the connection between anchoring part and abutment is at the marginal bone level. The term “at bone level” includes minor deviations from this level (e.g. 1 mm above or below said level). In any case, the anchoring part does not extend substantially above bone level. Said implant systems are favoured by patients due to their aesthetic advantages. However, the abutment of such implant system is in contact with soft tissue, and therefore it is important to establish an effective seal between oral environment and the endosseous part of the dental implant system.
A central property of dental implants is their osteointegration time, that is to say the time that passes before the bone substance has become connected with sufficient strength and permanently to the bone contact surface, that is to say has become integrated with it.
Therefore, much effort has been made in order to improve the osteointegration of said implants, such as described in EP 1 150 620. It was shown that the osteointegration time was significantly shorter if the bone contact surface of the implant is roughened, and in particular additionally hydroxylated and hydrophilic.
However, there is considerable evidence supporting the view that the supracrestal connective tissue plays a fundamental role in establishing an effective seal between the oral environment and the endosseous part of a dental implant. Indeed, the presence of bacteria on the implant surface or on the abutment surface may lead to an inflammation of the peri-implant mucosa, and, if left untreated, the inflammation spreads apically and results in bone resorption.
Biomaterials, 2005; 26(4): 373-81 discloses the influence of surface topography of ceramic abutments on the attachment and proliferation of human oral fibroblasts. It was shown, that polished surfaces had significantly higher percentages of initial cell attachment than the other surfaces.
J. Clin. Periodontol. 2002, 29 (5): 456-fl describes soft tissue reactions to plague formation at abutments with different surface topography. It was shown that different surface characteristics of abutments made of titanium failed to influence plague formation and the establishment of inflammatory cell lesions in the periimplant mucosa.
Different types of abutments for two-part implants are known in the art. U.S. Pat. No. 6,663,388 discloses a straight or an angular abutment which can be established by means of a base screw and a supporting ring.
U.S. Pat. No. 5,417,568 discloses an abutment for an implant of a dental prosthesis which is contoured to follow the to gingival margin. Said abutment can be fabricated from gold alloy, titanium alloy, or ceramic material. The surface of said abutment has not been treated.
U.S. Pat. No. 6,951,460 relates to an implant system including an abutment, an abutment replica and an impression coping. The abutments are intended to be connected to submerged implants.
It is the problem of the present invention to provide an abutment with improved soft tissue integration for a two part implant system, wherein the anchoring part of the implant system is submerged at bone level.